Is the u-boot-envs folder from a previous Yocto version or from Ubilinux version?
What is the behavior of the board when you try to use the Terminal Console? Have you tried to change the mode of the folder with chmod?
And, have you tried with the flash tool lite? Flash Tool Lite User Manual | Intel® Developer Zone
hi, CMata, When I flash on linux, I met this error. So I tried your method on windows, it worked!